1. Field of the Invention
The present invention relates to an apparatus for heating workpieces to be bonded together, such as a soldering apparatus.
2. Description of the Related Art
In manually soldering workpieces by means of a soldering iron, an operator must hold the iron in one hand and solder in the other. Therefore, if the workpieces to be bonded are a terminal and a lead wire, for example, the workpieces cannot be soldered unless an end portion of the lead wire is previously wound around the terminal. Thus, soldering the lead wire and the terminal requires very much time and labor.
If the operator unexpectedly touches the workpieces before molten solder is solidified by cooling, the soldering position of the workpieces sometimes may be dislocated from the object position, even though the workpieces have shapes such that they can easily mate with each other.
Skill of a high order is required to ensure electrical connection between the workpieces by soldering. It is very difficult for an unskilled operator, therefore, to effect stable, high-quality soldering.
Thus, if the soldering iron is unsatisfactorily heated, or if it is improperly contacted to the workpieces, the molten solder cannot smoothly diffuse, so that the solder may come off the workpieces or become lumpy. As a result, the workpieces may fail to be electrically connected, and if not, the soldered portion cannot enjoy a fine appearance or shape, and the bonding strength of the solder is subject to substantial variations.
In the soldering work using the soldering iron, as described above, the greatest possible care and high-order skill are required of the operator. Accordingly, excessive labor is forced upon the operator, and the cycle time required for each soldering operation is inevitably long.
The workpieces are expected to be heated not only in the soldering work described above, but also in workpiece bonding work using a hot-melt resin, bonding work based on resin caulking, etc. Conventionally, hot-blast heating or ultrasonic heating is used in these bonding operations except for the soldering work. These heating methods, however, require a long time to heat the workpieces, as well as use of bulky equipment, so that the operating time for the bonding work cannot be shortened.